// Boost.Geometry (aka GGL, Generic Geometry Library)

// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.

// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.

// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_GEOMETRY_STRATEGIES_TRANSFORM_MAP_TRANSFORMER_HPP
#define BOOST_GEOMETRY_STRATEGIES_TRANSFORM_MAP_TRANSFORMER_HPP


#include <cstddef>

#include <boost/geometry/strategies/transform/matrix_transformers.hpp>


namespace boost { namespace geometry
{

namespace strategy { namespace transform
{

/*!
\brief Transformation strategy to do map from one to another Cartesian system
\ingroup strategies
\tparam P1 first point type
\tparam P2 second point type
\tparam Mirror if true map is mirrored upside-down (in most cases pixels
    are from top to bottom, while map is from bottom to top)
 */
template
<
    typename P1, typename P2,
    bool Mirror = false, bool SameScale = true,
    std::size_t Dimension1 = dimension<P1>::type::value,
    std::size_t Dimension2 = dimension<P2>::type::value
>
class map_transformer
    : public ublas_transformer<P1, P2, Dimension1, Dimension2>
{
    typedef typename select_coordinate_type<P1, P2>::type T;
    typedef boost::numeric::ublas::matrix<T> M;

public :
    template <typename B, typename D>
    explicit inline map_transformer(B const& box, D const& width, D const& height)
    {
        set_transformation(
                get<min_corner, 0>(box), get<min_corner, 1>(box),
                get<max_corner, 0>(box), get<max_corner, 1>(box),
                width, height);
    }

    template <typename W, typename D>
    explicit inline map_transformer(W const& wx1, W const& wy1, W const& wx2, W const& wy2,
                        D const& width, D const& height)
    {
        set_transformation(wx1, wy1, wx2, wy2, width, height);
    }


private :
    template <typename W, typename P, typename S>
    inline void set_transformation_point(W const& wx, W const& wy,
        P const& px, P const& py,
        S const& scalex, S const& scaley)
    {

        // Translate to a coordinate system centered on world coordinates (-wx, -wy)
        M t1(3,3);
        t1(0,0) = 1;   t1(0,1) = 0;   t1(0,2) = -wx;
        t1(1,0) = 0;   t1(1,1) = 1;   t1(1,2) = -wy;
        t1(2,0) = 0;   t1(2,1) = 0;   t1(2,2) = 1;

        // Scale the map
        M s(3,3);
        s(0,0) = scalex;   s(0,1) = 0;   s(0,2) = 0;
        s(1,0) = 0;    s(1,1) = scaley;  s(1,2) = 0;
        s(2,0) = 0;    s(2,1) = 0;      s(2,2) = 1;

        // Translate to a coordinate system centered on the specified pixels (+px, +py)
        M t2(3, 3);
        t2(0,0) = 1;   t2(0,1) = 0;   t2(0,2) = px;
        t2(1,0) = 0;   t2(1,1) = 1;   t2(1,2) = py;
        t2(2,0) = 0;   t2(2,1) = 0;   t2(2,2) = 1;

        // Calculate combination matrix in two steps
        this->m_matrix = boost::numeric::ublas::prod(s, t1);
        this->m_matrix = boost::numeric::ublas::prod(t2, this->m_matrix);
    }


    template <typename W, typename D>
    void set_transformation(W const& wx1, W const& wy1, W const& wx2, W const& wy2,
                    D const& width, D const& height)
    {
        D px1 = 0;
        D py1 = 0;
        D px2 = width;
        D py2 = height;

        // Get the same type, but at least a double
        typedef typename select_most_precise<D, double>::type type;


        // Calculate appropriate scale, take min because whole box must fit
        // Scale is in PIXELS/MAPUNITS (meters)
        W wdx = wx2 - wx1;
        W wdy = wy2 - wy1;
        type sx = (px2 - px1) / boost::numeric_cast<type>(wdx);
        type sy = (py2 - py1) / boost::numeric_cast<type>(wdy);

        if (SameScale)
        {
            type scale = (std::min)(sx, sy);
            sx = scale;
            sy = scale;
        }

        // Calculate centerpoints
        W wtx = wx1 + wx2;
        W wty = wy1 + wy2;
        W two = 2;
        W wmx = wtx / two;
        W wmy = wty / two;
        type pmx = (px1 + px2) / 2.0;
        type pmy = (py1 + py2) / 2.0;

        set_transformation_point(wmx, wmy, pmx, pmy, sx, sy);

        if (Mirror)
        {
            // Mirror in y-direction
            M m(3,3);
            m(0,0) = 1;   m(0,1) = 0;   m(0,2) = 0;
            m(1,0) = 0;   m(1,1) = -1;  m(1,2) = 0;
            m(2,0) = 0;   m(2,1) = 0;   m(2,2) = 1;

            // Translate in y-direction such that it fits again
            M y(3, 3);
            y(0,0) = 1;   y(0,1) = 0;   y(0,2) = 0;
            y(1,0) = 0;   y(1,1) = 1;   y(1,2) = height;
            y(2,0) = 0;   y(2,1) = 0;   y(2,2) = 1;

            // Calculate combination matrix in two steps
            this->m_matrix = boost::numeric::ublas::prod(m, this->m_matrix);
            this->m_matrix = boost::numeric::ublas::prod(y, this->m_matrix);
        }
    }
};


}} // namespace strategy::transform


}} // namespace boost::geometry


#endif // BOOST_GEOMETRY_STRATEGIES_TRANSFORM_MAP_TRANSFORMER_HPP
